View Full Version : Port Displacement

10-23-2005, 12:08 AM
im doin a box for a 15'' L7. using 4 inch aeroports, tuned @ 32 hz.

i need to know the formula to figure out how many cubic feet the port displaces.

can somebody post it for me?


10-23-2005, 10:42 AM
The formula for figuring displacement of a vent is as follows:
Vent Displacement = (1/2 the outside diameter X 2) X 3.14 X length of
the vent
For example, a 4" port, 5" long would figure like this: (a typical 4" port
has an outside diameter of 4.5"): 2.25 X 2.25 X 3.14 X 5.0 = 78.46
cubic inches of displacement!

here is a link to an exelent tutorial. LINK (http://www.rockfordfosgate.com/rftech/enclosure/RFTECH_enclosure_v2002.pdf)